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This paper is concerned with the study of silica fume that arises in tonnage amounts during the manufacture of ferrosilicon alloys; this was done in order to maximize productivity and to create new market for industrial by‐product and/or waste material.

The structure and particle shape of silica fume were identified using X‐ray diffraction and electron microscope, respectively. Standard methods were used for the identification of chemical analyses, solubility, hydrogen ion concentration, specific gravity, bulking value, oil absorption, chemical resistance and particle size. The characterized and evaluated silica fume was applied in several paint formulations. The physico‐mechanical, chemical and corrosion protective properties of the paint films were measured according to standard methods.

The silica fume under investigation was a fine lightweight fluffy amorphous powder. It has a grayish‐white color that makes it suitable for use as a filler and extender pigment in a wide variety of different fields of application; its amorphous nature favors safe use from a standpoint of industrial hygiene. It can be used as an economic pigment that possesses suitable values of specific gravity, bulking value and oil absorption. It also is inert, neutral and of an excellent chemical resistance. The material can be used successfully as an extender pigment in different paint formulations; taking into consideration that alkyd resin based paints should not be used in alkaline environments or mixed with basic pigments, or the paint film will deteriorate. Silica fume particles in the pigment mixture may offer a suitable opportunity for the voids formed by the larger particles to be occupied by smaller ones to produce a condition of maximum packing. It can be successfully used with the flaky aluminum or stainless steel anticorrosive pigments to produce a highly efficient corrosion protective film.

There is increasing environmental concern with regard to excessive volumes of solid waste hazards accumulation. Silica fume that arises – as a disposal material – in tonnage amounts during the manufacture of ferrosilicon alloys can find a new market in paint industry. It can be used successfully for anticorrosive paints to provide well backed paint films.

Core-shell is structured particles having several chemical compositions. The advantage of these particles arise from their specific design, to be used in decreasing costs by using inexpensive material (natural ore or waste material) as carrier for thin shell of active material. This study aims to prepare ferrites/silica core-shell pigments and compare their inhibition efficiency to original ferrites. These pigments have shells of different ferrites that comprise 10-15 per cent of the prepared pigments on silica fume. Silica fume which is the core is a byproduct in the ferro–silicon industry; this core comprises 85-90 per cent of the prepared pigments.

The prepared core-shell pigments were characterized using transmission electron microscopy analysis, energy-dispersive X-ray analysis and sequential wavelength dispersive X-ray fluorescence. These pigments were integrated in epoxy-based paint formulations, and the physical, mechanical and corrosion properties of dry films were examined. The corrosion properties were studied by using immersion test in 3.5 per cent NaCl for 28 days.

This study showed that these new eco-friendly and inexpensive pigments are similar to ferrites in their inhibition performance, i.e. they exhibited high corrosion prevention.

Domestic waste materials were reused in paints and only simple modification was used, and then, their effectiveness showed similar performance to that of the original pigments.

Ferrite and ferrite/silica pigments are environmentally friendly pigments that can replace other hazardous pigments (e.g. chromates) with almost the same quality in their performance; also, they can be used in industries other than paints (e.g. paper, rubber and plastics composites).

Responses to open‐ended questions concerning sources of work satisfaction among social workers indicate that instruments and methodology which have been devised in industrial settings may create distortions when applied to human services. The most important sources of satisfaction and dissatisfaction differ from those elicited in industry, a fact which points out the need to begin detailed research in the service sector using workers' own conceptions of their situation rather than preconceptions drawn from other areas of work.

In this paper, the main focus is on supply and demand auction systems with resource pooling in modern supply chain from a theoretical modeling perspective. The supply and demand auction systems in modern supply chains among manufacturers and suppliers serve as information sharing mechanisms. The purpose of this paper is to match the supply and demand such that a modern supply chain can achieve incentive compatibility and economic efficiency. The authors design such a supply and demand auction system that can integrate resources to efficiently match the supply and demand.

The authors propose three theoretic models of modern supply chain auctions with resource pooling according to the Vickrey auction principle. They are supply auction model with demand resource pooling, demand auction model with supply resource pooling, and double auction model with demand and supply resource pooling. For the proposed auction models, the authors present three corresponding algorithms to allocate resources in the auction process by linear programming, and study the incentive compatibility and define the Walrasian equilibriums for the proposed auction models. The authors show that the solutions of the proposed algorithms are Walrasian equilibriums.

By introducing the auction mechanism, the authors aim to realize the following three functions. First is price mining: auction is an open mechanism with multiple participants. Everyone has his own utility and purchasing ability. So, the final price reflects the market value of the auction. Second is dynamic modern supply chain construction: through auction, firm can find appropriate partner efficiently. Third is resources integration: in business practices, especially in modern supply chain auctions, auctioneers can integrate resources and ally buyers or sellers to gain more efficiency in auctions.

In the paper, the authors propose three theoretic models and corresponding algorithms of modern supply chain auctions with resource pooling according using the Vickrey auction principle, which achieves three functions: price mining, dynamic modern supply chain construction and resources integrating. Besides, these proposed models are much closer to practical settings and may have potential applications in modern supply chain management.

Social services in most western democracies find themselves in recent years in the midst of diminishing public resources due to economic, demographic and political changes. Phenomena such as slowed economic growth, inflation, unemployment, and the exhaustion of public treasuries have become the daily diet of a number of Western countries (Specht, 1981; Norsworthy et al., 1979; Hakim, 1982).

Using Becker's ‘taste for discrimination’ model, the chapter analyzes the current legislation against wage discrimination and finds it counterproductive. Using a costly apparatus of auditing, detecting and fining violators does not deliver results. If a fine is levied on discriminators and reimbursed to the disadvantaged workers in order to undo the discrimination, it affects equally the demand for and the supply of those workers, because their expected wage includes the fine, and has no real effect. If the fine is collected and kept by the government, it shifts employment away from the workers it seeks to help, to others, depressing the total employment. In contrast, levying a tax on the favored workers effectively curbs discrimination in the labor market. A quota is a possible substitute for a tax with questionable side effects. Affirmative action is in essence a sort of tax on employing favored workers, only administered in an indirect, clumsy and costly way. Yet, the chapter explains its humble impact in the right direction. An explicit and direct tax would do much more and with a negative cost. Alternatively, subsidizing the disfavored workers is a costly but as effective policy that, in addition, boosts total employment.

This paper examines the effect of intergroup competition on intragroup cooperation. Three experiments are reviewed. The first experiment establishes that intergroup competition can effectively increase intragroup cooperation in a laboratory setting where symmetric players make binary decisions in one‐shot dilemma games. The second experiment shows that this constructive effect of intergroup competition is generalizable to a real‐life setting in which asymmetric players make continuous decisions in an ongoing interaction. The third experiment demonstrates that the increase in intragroup cooperation can be accounted for at least in part by motivational, rather than structural, effects of the intergroup competition. Theoretical and practical issues concerning the applications of these findings are discussed.

The purpose of this paper is to solve unsteady compressible Navier–Stokes equations without the commonly used dual-time loop. The authors would like to use an adaptive time-stepping (ATS)-based local error control instead of CFL-based time-stepping technique. Also, an all-speed flow algorithm is implemented with simple low dissipation AUSM convective scheme, which can be computed without preconditioning which in general destroys the time accuracy.

In transient flow computations, the time-step is generally determined from the CFL condition. In this paper, the authors demonstrate the usefulness of ATS based on local time-stepping previously used extensively in ordinary differential equations (ODE) integration. This method is implemented in an implicit framework to ensure the numerical domain of dependence always contains the physical domain of dependence.

In this paper, the authors limit their focus to capture the unsteady physics for three cases: Sod’s shock-tube problem, Stokes’ second problem and a circular cylinder. The use of ATS with local truncation error control enables the solver to use the maximum allowable time-step, for the prescribed tolerance of error. The algorithm is also capable of converging very rapidly to the steady state (if there is any) after the initial transient phase. The authors present here only the first-order time-stepping scheme. An algorithmic comparison is made between the proposed adaptive time-stepping method and the commonly used dual time-stepping approach that indicates the former will be more efficient.

The original method of ATS based on local error control is used extensively in ODE integration, whereas, this method is not so popular in the computational fluid dynamics (CFD) community. In this paper, the authors investigate its use in the unsteady CFD computations. The authors hope that it would provide CFD researchers with an algorithm based on an adaptive time-stepping approach for unsteady calculations.

This study investigated the association between structural conditions and social incentives and their effect on the ethnic composition of mobile social networks. Regarding structural conditions, we examined the role of the ethnic group’s size, socioeconomic status, and heterogeneity of the city in which the business was located. Regarding social incentives, we investigated the social diversification hypothesis, which expects that residentially and socially segregated minority groups will take advantage of mobile communications to diversify their mobile communication ties with outgroup members.

Two data sets were used. The first was the aggregation of the mobile communication patterns of business customers as measured by one of Israel’s mobile phone operators in April 2010. The database included 9,099 call data records. The second was a data set of the social characteristics of 103 Israeli cities from the Israeli Bureau of Statistics. Both data sets were merged according to the place of residence of each customer.

Israeli Arab businesses in homogeneous Jewish and mixed cities operate in an environment with more structural opportunities to create outgroup ethnic ties than Arab businesses in homogeneous Arab cities. Jewish businesses in ethnically mixed cities have more outgroup mobile ties than comparable businesses in homogenous Jewish cities.

We expand previous models and suggest a structural diversification approach in which ethnic mobile social networks vary across homogeneous and ethnically mixed cities. These variations result in different social incentives as the diversification approach assumed, as well as different structural conditions, as the structural approach indicates.

The relationship between intergroup conflict and intragroup cohesion is a longstanding concern in sociology and related disciplines. Past work suggests that intergroup conflict shapes emotional bonds between group members, promotes in-group and out-group stereotyping, encourages self-sacrifice for the group, and changes the social structure of groups. Conflict thus plays an important structural role in organizing social interaction. Although sociologists contributed much to the beginnings of this research tradition, sociological attention to the conflict–cohesion link has waned in recent decades. We contend that despite advances in our understanding of the conflict–cohesion hypothesis, more remains to be done, and sociologists are especially equipped to tackle these unanswered questions. As such, we encourage sociologists to revisit the study of intergroup conflict and intragroup cohesion and offer some possibilities for furthering our understanding of this phenomenon. After reviewing and evaluating the relevant literatures on the conflict–cohesion hypothesis, we consider ways in which a broad range of current theories from the group process tradition – including theories of status, exchange, justice, identity, and emotion – could contribute to understanding the conflict–cohesion hypothesis and how those theories could benefit from considering the conflict–cohesion hypothesis. In doing so, we make a case for the continuing importance of sociology in explaining the link between intergroup conflict and intragroup cohesion.